<Background Art 1>
A base station device is provided with a scheduler that performs scheduling to determine radio resources (frequencies, times, and the like) to be allocated to terminal devices.
The scheduler enables to appropriately determine allocation of radio resources to each terminal in accordance with the radio wave condition or the like.
In LTE (Long Term Evolution), the scheduler is configured as a function of MAC (Media Access Control; second layer) for wireless communication, i.e., as a MAC scheduler.
FIG. 9 illustrates a layer structure relating to wireless communication of a base station device in the LTE. This layer structure includes PHY (Physical Layer) as a first layer relating to wireless communication, and MAC as a layer higher than the PHY. The scheduler is a function of the MAC.
RLC (Radio Link Control)/PDCP (Packet Data Convergence Protocol) is provided above the MAC. The RLC (Radio Link Control) has a signal retransmission function and the like, and the PDCP (Packet Data Convergence Protocol) has a security function and the like (refer to Non-Patent Literature 1).
Further, RRC (Radio Resource Control), RRM (Radio Resource Management), and NAS (Non-Access Stratum) are provided above the RLC/PDCP.
As described above, in the LTE, the functions relating to management of radio resources, such as the RRC (Radio Resource Control) and the RRM (Radio Resource Management), are provided in the base station device.
The RRM included in the layers above the MAC manages the radio resources, and provides the MAC scheduler with information required for scheduling (schedule information). The schedule information provided from the RRM includes QoS (Quality of Service) information and the like.
The PHY as a layer lower than the MAC obtains CQI (Channel Quality Indicator) information, and the CQI information is sometimes provided as schedule information to the MAC scheduler.
<Background Art 2>
Generally, a base station device is provided with a scheduler that determines radio resources (frequencies, times, and the like) to be allocated to terminal devices.
As a conventional scheduling algorithm for determining allocation of radio resources, for example, round robin is known (refer to Non-Patent Literature 2). In the round robin scheduling, almost the same amount of radio resources are allocated to terminal devices (users) in order.
Meanwhile, proportional fairness is also known as a scheduling algorithm, in which allocation of radio resources is performed in consideration of the quality values of communication with terminal devices.
<Background Art 3>
In a wireless communication system having a plurality of base station devices, if communication areas (cells) set by the respective base station devices overlap each other, a signal transmitted from a certain base station device may reach a terminal device existing in a cell of another base station device located near the base station device, and the signal may become an interference signal for the terminal device.
It is well known that such interference can be suppressed by beam forming. That is, by performing beam forming such that a beam is directed to a terminal device (hereinafter also referred to as “own terminal device”) existing in a cell of the (certain) base station device while a null beam is directed to the terminal device (hereinafter also referred to as “another terminal device”) existing in the cell of the another base station device, the signal (interference signal) from the (certain) base station device becomes less likely to reach the another terminal device, thereby suppressing interference (refer to Non-Patent Literature 3 for beam forming).